Intratumoural Treatment of 18 Cytologically Diagnosed Canine High-Grade Mast Cell Tumours With Tigilanol Tiglate

Response to tigilanol tiglate in dogs with mast cell tumors

BACKGROUND

Information regarding response rate to tigilanol tiglate for mast cell tumors in dogs is limited.

OBJECTIVES

Report the response rate and durability of tigilanol tiglate intratumoral treatment in dogs with mast cell tumors presented to veterinary oncologists.

ANIMALS

One hundred forty-nine dogs; 151 individual tumors.

METHODS

Multicenter, retrospective survey-based study. Veterinary oncologists subscribed to the American College of Veterinary Internal Medicine (ACVIM) oncology listserv were solicited for information from dogs treated with tigilanol tiglate. An electronic survey was used to collect information at initial treatment, 1 month and 1 year after treatment.

RESULTS

Most tumors were cutaneous, occurred on the limbs and were cytologically low grade. Seventy-five percent of dogs achieved a complete response after 1 dose of tigilanol tiglate 1 month after treatment. This response was durable at 1 year in 64% of dogs for which data were available (n = 88). Wound formation, an expectation after treatment, occurred after a median of 7 days (range, 1-91 days), with a median wound area of 4.71 cm2 (range, 0.09-100 cm2). Wounds took a median of 30 days to heal completely (range, 14-154 days). A moderate association between tumor volume and wound size was confirmed.

CONCLUSIONS AND CLINICAL IMPORTANCE

Tigilanol tiglate is an effective local treatment option for mast cell tumors in dogs with a predictable clinical course and response. Because of the unique mode of action and clinical course, client education and careful case selection is necessary before electing tigilanol tiglate for local treatment.

New Therapies in Veterinary Oncology

The expanding number of specialized oncology therapeutics available in veterinary oncology can make staying updated on the most recent advances challenging. This article summarizes the mechanism of action, available supporting data, and clinical use of three key veterinary cancer/supportive care therapeutics: Laverdia-CA1, Canalevia-CA1, and Stelfonta. This information will help guide clinical use within your practice and can be incorporated into discussions with clients regarding the newest available options for their dogs with cancer.

Tigliane Diterpenoids

The distribution, chemistry, and molecular bioactivity of tiglianes are reviewed from the very beginning of the studies on these diterpenoids, summarizing their clinical and toxicological literature mostly in its more recent and controversial aspects, and critically analyzing various proposals for their biosynthesis.

Treatment of multiple synchronous canine mast cell tumours using intratumoural tigilanol tiglate

Mast cell tumours (MCTs) are common canine skin neoplasia. While they generally occur as single tumours, multiple synchronous MCTs (msMCTs) of de novo/non-metastatic origin are reported in a proportion of the patient population. Where there is no evidence of metastasis or lymphatic spread, MCTs are effectively controlled by surgery and other local therapies. However, treatment of de novo msMCTs can be more challenging, especially when they occur in surgically difficult locations. Here, we report the use of tigilanol tiglate, a novel small molecule registered as a veterinary pharmaceutical for the local treatment of non-metastatic MCTs, in the treatment of patients with msMCTs presenting at three Australian specialist referral centres. We also present a meta-analysis of the literature to provide a better understanding of the prevalence of canine msMCTs. Notably, nine patients with a total of 32 MCTs were treated during the study. A complete response was recorded in 26 (81%) of the individual MCTs on Day 28 after a single tigilanol tiglate injection. Of the 6 initially non-responsive MCTs, one achieved a complete response after a further tigilanol tiglate treatment. A complete response was reported at 6 months in all 22 of the tumours that were evaluable and that had recorded a complete response at Day 84. For the literature meta-analysis, 22 studies were found with prevalence estimates of msMCTs ranging from 3 to 40%; when combined, these studies yielded 3,745 patients with a prevalence of 13% (95% CI 10; 16). Overall, the results demonstrate the utility of intratumoural tigilanol tiglate as an option for the treatment of multiple MCTs where multiple surgical resections would have been required.

Identification of Gene Biomarkers for Tigilanol Tiglate Content in Fontainea picrosperma

Tigilanol tiglate (EBC-46) is a small-molecule natural product under development for the treatment of cancers in humans and companion animals. The drug is currently produced by purification from the Australian rainforest tree Fontainea picrosperma (Euphorbiaceae). As part of a selective-breeding program to increase EBC-46 yield from F. picrosperma plantations, we investigated potential gene biomarkers associated with biosynthesis of EBC-46. Initially, we identified individual plants that were either high (>0.039%) or low EBC-46 (<0.008%) producers, then assessed their differentially expressed genes within the leaves and roots of these two groups by quantitative RNA sequencing. Compared to low EBC-46 producers, high-EBC-46-producing plants were found to have 145 upregulated genes and 101 downregulated genes in leaves and 53 upregulated genes and 82 downregulated genes in roots. Most of these genes were functionally associated with defence, transport, and biosynthesis. Genes identified as expressed exclusively in either the high or low EBC-46-producing plants were further validated by quantitative PCR, showing that cytochrome P450 94C1 in leaves and early response dehydration 7.1 and 2-alkenal reductase in roots were consistently and significantly upregulated in high-EBC-46 producers. In summary, this study has identified biomarker genes that may be used in the selective breeding of F. picrosperma.

Diagnosis, Prognosis and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors

Mast cell tumors (MCTs) are hematopoietic neoplasms composed of mast cells. It is highly common in dogs and is extremely important in the veterinary oncology field. It represents the third most common tumor subtype, and is the most common malignant skin tumor in dogs, corresponding to 11% of skin cancer cases. The objective of this critical review was to present the report of the 2nd Consensus meeting on the Diagnosis, Prognosis, and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors, which was organized by the Brazilian Association of Veterinary Oncology (ABROVET) in August 2021. The most recent information on cutaneous and subcutaneous mast cell tumors in dogs is presented and discussed.